KISSIMMEE, Fla. -- There's no better way to motivate Jarred Cosart than to tell him he can't do something. How else do you explain a kid who was drafted in the 38th round of the First-Year Player Draft -- an afterthought, really -- becoming one the Astros' top pitchers a year ago?

Few people outside Cosart's circle thought he'd reach the Majors, much less flirt with a no-hitter in his debut and post the lowest ERA through 10 starts by an Astros pitcher in franchise history. Simply put, he's defied the odds time and again.

So when a blogger earlier this year said that Cosart was likely to regress from his rookie numbers -- he went 1-1 with a 1.95 ERA in 10 starts -- Cosart took that as a challenge as well.

"I know my expectations are high," he said. "That's all I'm worried about. I see a lot of people expect a big regression, because they think I got lucky with the walks and stuff, so it's just using that as motivation and believing in myself and what these guys are teaching me. That's what I'm going to take out on the field."

Cosart, the Houston-area product who was acquired from the Phillies in the Hunter Pence trade in 2011, set the bar high when he held the Rays to two hits in eight scoreless innings in his July 12 Major League debut, outdueling David Price in the process.

He set a franchise record by pitching at least five innings and allowing no more than three runs in his first eight Major League starts. In 60 innings, he allowed 46 hits and 13 earned runs, though he did have more walks (35) than strikeouts (33).

"Performance is performance," manager Bo Porter said. "A lot of guys get in trouble, but don't have the stuff to get out of it. I think it speaks volumes that he was able to use this stuff and use the defense and allow them to make plays. You look at times last year, and he was able to get a lot of double-play balls."

Still, Cosart knows he needs more control to go along with his power arm, which is why he was willing to tinker with his mechanics in the offseason. Bullpen coach Craig Bjornson watched video of his starts against the Rays and A's last year, and he noticed Cosart was more effective when he wasn't quite so upright in his delivery -- when his body "went off line" and came back, as pitching coach Brent Strom explained.

That's why Cosart now has his hands lower at the beginning of his windup instead of up around his chest.

"What it does is it allows the body to rotate better, better angles and things like that," Strom said.

The adjustment was relatively minor, but Cosart has been working on it all spring and threw two scoreless innings Sunday in his Grapefruit League debut against the Braves.

"It just gives me something more clean to get out of my glove and get the ball down, and I had a lot more angle on my fastball today and [liked] the feedback with some of the hitters' swings," he said.

Cosart, to cut down on walks, is also trying to throw more first-pitch strikes, and is going as far as to scribble "Attack the zone" on the inside of his cap and locker as a daily reminder.

"That's kind of what Strom's base point for me is -- use your stuff to your advantage and attack your zone, and if you pitch ahead, you're going to have a lot more success," he said.

Even if Cosart does regress somewhat, he could still be a huge part of the Astros' rotation. General manager Jeff Luhnow said if he picks up where he left off last year, the club would be thrilled. That being said, teams now have more video and scouting reports on him and hitters will be able to adjust.

"He's going to have to keep them guessing as well," Luhnow said. "He certainly has all the repertoire and pitches to be a dominant starter at the big league level, and he showed that last year. Now comes the adjustment period, and sometimes it takes guys longer than others.

"Sophomore slump is always a possibility for guys who had a good first year, but I think between his capabilities, our catching staff and our pitching coaches, I think he's going to be able to make the adjustments he needs. I expect him to be in the rotation this year, and I think he's capable of winning 15 games this year."

Cosart, 23, and left-hander Brett Oberholtzer are in the same boat, having impressed in their Major League debuts last year while making only 10 starts. Their careers are still in front of them, and having a full year in the rotation to show what they can or can't do is what's ahead in 2014.

"We were champing at the bit to get up here, and when we got up here, we wanted to prove we could pitch here," Cosart said. "It's a small sample size. There's a lot of messing around in the clubhouse about service time with guys like [Chad] Qualls and [Scott] Feldman, so we know we've got a lot of work ahead of us and a long way to go."